systemd.netdev man page
systemd.netdev — Virtual Network Device configuration
Network setup is performed by systemd-networkd(8).
Virtual Network Device files must have the extension
.netdev; other extensions are ignored. Virtual network devices are created as soon as networkd is started. If a netdev with the specified name already exists, networkd will use that as-is rather than create its own. Note that the settings of the pre-existing netdev will not be changed by networkd.
.netdev files are read from the files located in the system network directory
/usr/lib/systemd/network, the volatile runtime network directory
/run/systemd/network and the local administration network directory
/etc/systemd/network. All configuration files are collectively sorted and processed in lexical order, regardless of the directories in which they live. However, files with identical filenames replace each other. Files in
/etc have the highest priority, files in
/run take precedence over files with the same name in
/usr/lib. This can be used to override a system-supplied configuration file with a local file if needed; a symlink in
/etc with the same name as a configuration file in
/usr/lib, pointing to
/dev/null, disables the configuration file entirely.
Supported netdev kinds
The following kinds of virtual network devices may be configured in
Table 1. Supported kinds of virtual network devices
|bond||A bond device is an aggregation of all its slave devices. See Linux Ethernet Bonding Driver HOWTO for details.Local configuration|
|bridge||A bridge device is a software switch, each of its slave devices and the bridge itself are ports of the switch.|
|dummy||A dummy device drops all packets sent to it.|
|gre||A Level 3 GRE tunnel over IPv4. See RFC 2784 for details.|
|gretap||A Level 2 GRE tunnel over IPv4.|
|ip6gre||A Level 3 GRE tunnel over IPv6.|
|ip6tnl||An IPv4 or IPv6 tunnel over IPv6|
|ip6gretap||An Level 2 GRE tunnel over IPv6.|
|ipip||An IPv4 over IPv4 tunnel.|
|ipvlan||An ipvlan device is a stacked device which receives packets from its underlying device based on IP address filtering.|
|macvlan||A macvlan device is a stacked device which receives packets from its underlying device based on MAC address filtering.|
|sit||An IPv6 over IPv4 tunnel.|
|tap||A persistent Level 2 tunnel between a network device and a device node.|
|tun||A persistent Level 3 tunnel between a network device and a device node.|
|veth||An ethernet tunnel between a pair of network devices.|
|vlan||A VLAN is a stacked device which receives packets from its underlying device based on VLAN tagging. See IEEE 802.1Q for details.|
|vti||An IPv4 over IPSec tunnel.|
|vti6||An IPv6 over IPSec tunnel.|
|vxlan||A virtual extensible LAN (vxlan), for connecting Cloud computing deployments.|
[Match] Section Options
A virtual network device is only created if the
[Match] section matches the current environment, or if the section is empty. The following keys are accepted:
- Matches against the hostname or machine ID of the host. See
ConditionHost=in systemd.unit(5) for details.
- Checks whether the system is executed in a virtualized environment and optionally test whether it is a specific implementation. See
ConditionVirtualization=in systemd.unit(5) for details.
- Checks whether a specific kernel command line option is set (or if prefixed with the exclamation mark unset). See
ConditionKernelCommandLine=in systemd.unit(5) for details.
- Checks whether the system is running on a specific architecture. See
ConditionArchitecture=in systemd.unit(5) for details.
[NetDev] Section Options
[NetDev] section accepts the following keys:
- A free-form description of the netdev.
- The interface name used when creating the netdev. This option is compulsory.
- The netdev kind. This option is compulsory. See the
Supported netdev kindssection for the valid keys.
- The maximum transmission unit in bytes to set for the device. The usual suffixes K, M, G, are supported and are understood to the base of 1024. This key is not currently supported for
- The MAC address to use for the device. If none is given, one is generated based on the interface name and the machine-id(5). This key is not currently supported for
[VLAN] Section Options
[VLAN] section only applies for netdevs of kind
vlan, and accepts the following key:
- The VLAN ID to use. An integer in the range 0–4094. This option is compulsory.
[MACVLAN] Section Options
[MACVLAN] section only applies for netdevs of kind
macvlan, and accepts the following key:
- The MACVLAN mode to use. The supported options are
[IPVLAN] Section Options
[IPVLAN] section only applies for netdevs of kind
ipvlan, and accepts the following key:
- The IPVLAN mode to use. The supported options are
[VXLAN] Section Options
[VXLAN] section only applies for netdevs of kind
vxlan, and accepts the following keys:
- The VXLAN ID to use.
- An assigned multicast group IP address.
- The Type Of Service byte value for a vxlan interface.
- A fixed Time To Live N on Virtual eXtensible Local Area Network packets. N is a number in the range 1-255. 0 is a special value meaning that packets inherit the TTL value.
- A boolean. When true, enables dynamic MAC learning to discover remote MAC addresses.
- The lifetime of Forwarding Database entry learnt by the kernel in seconds.
- A boolean. When true, enables ARP proxy.
- A boolean. When true, enables netlink LLADDR miss notifications.
- A boolean. When true, enables netlink IP ADDR miss notifications.
- A boolean. When true route short circuit is turned on.
- A boolean. When true transmitting UDP checksums when doing VXLAN/IPv4 is turned on.
- A boolean. When true sending zero checksums in VXLAN/IPv6 is turned on.
- A boolean. When true receiving zero checksums in VXLAN/IPv6 is turned on.
[Tunnel] Section Options
[Tunnel] section only applies for netdevs of kind
ip6tnl and accepts the following keys:
- A static local address for tunneled packets. It must be an address on another interface of this host.
- The remote endpoint of the tunnel.
- The Type Of Service byte value for a tunnel interface. For details about the TOS see the Type of Service in the Internet Protocol Suite document.
- A fixed Time To Live N on tunneled packets. N is a number in the range 1-255. 0 is a special value meaning that packets inherit the TTL value. The default value for IPv4 tunnels is: inherit. The default value for IPv6 tunnels is: 64.
- A boolean. When true, enables Path MTU Discovery on the tunnel.
ip6tnltunnels can have three modes
ip6ip6for IPv6 over IPv6,
ipip6for IPv4 over IPv6 or
[Peer] Section Options
[Peer] section only applies for netdevs of kind
veth and accepts the following key:
- The interface name used when creating the netdev. This option is compulsory.
- The peer MACAddress, if not set it is generated in the same way as the MAC address of the main interface.
[Tun] Section Options
[Tun] section only applies for netdevs of kind
tun, and accepts the following keys:
- Takes a boolean argument. Configures whether all packets are queued at the device (enabled), or a fixed number of packets are queued at the device and the rest at the
qdisc. Defaults to
- Takes a boolean argument. Configures whether to use multiple file descriptors (queues) to parallelize packets sending and receiving. Defaults to
- Takes a boolean argument. Configures whether packets should be prepended with four extra bytes (two flag bytes and two protocol bytes). If disabled it indicates that the packets will be pure IP packets. Defaults to
- Takes a boolean argument. Configures IFF_VNET_HDR flag for a tap device. It allows sending and receiving larger Generic Segmentation Offload (GSO) packets. This may increase throughput significantly. Defaults to
- User to grant access to the
- Group to grant access to the
[Tap] Section Options
[Tap] section only applies for netdevs of kind
tap, and accepts the same keys as the
[Bond] Section Options
[Bond] section accepts the following key:
- Specifies one of the bonding policies. The default is
balance-rr(round robin). Possible values are
- Selects the transmit hash policy to use for slave selection in balance-xor, 802.3ad, and tlb modes. Possible values are
- Specifies the rate with which link partner transmits Link Aggregation Control Protocol Data Unit packets in 802.3ad mode. Possible values are
slow, which requests partner to transmit LACPDUs every 30 seconds, and
fast, which requests partner to transmit LACPDUs every second. The default value is
- Specifies the frequency that Media Independent Interface link monitoring will occur. A value of zero disables MII link monitoring. This values is rounded down to the nearest millisecond. The default value is 0.
- Specifies the delay before a link is enabled after a link up status has been detected. This value is rounded down to a multiple of MIIMonitorSec. The default value is 0.
- Specifies the delay before a link is disabled after a link down status has been detected. This value is rounded down to a multiple of MIIMonitorSec. The default value is 0.
- Specifies the number of seconds between instances where the bonding driver sends learning packets to each slaves peer switch. The valid range is 1 - 0x7fffffff; the default value is 1. This Option has effect only in balance-tlb and balance-alb modes.
- Specifies the 802.3ad aggregation selection logic to use. Possible values are
- Specifies whether active-backup mode should set all slaves to the same MAC address at enslavement or, when enabled, perform special handling of the bond's MAC address in accordance with the selected policy. The default policy is none. Possible values are
- Specifies whether or not ARP probes and replies should be validated in any mode that supports ARP monitoring, or whether non-ARP traffic should be filtered (disregarded) for link monitoring purposes. Possible values are
- Specifies the ARP link monitoring frequency in milliseconds. A value of 0 disables ARP monitoring. The default value is 0.
- Specifies the IP addresses to use as ARP monitoring peers when ARPIntervalSec is greater than 0. These are the targets of the ARP request sent to determine the health of the link to the targets. Specify these values in ipv4 dotted decimal format. At least one IP address must be given for ARP monitoring to function. The maximum number of targets that can be specified is 16. The default value is no IP addresses.
- Specifies the quantity of ARPIPTargets that must be reachable in order for the ARP monitor to consider a slave as being up. This option affects only active-backup mode for slaves with ARPValidate enabled. Possible values are
- Specifies the reselection policy for the primary slave. This affects how the primary slave is chosen to become the active slave when failure of the active slave or recovery of the primary slave occurs. This option is designed to prevent flip-flopping between the primary slave and other slaves. Possible values are
- Specifies the number of IGMP membership reports to be issued after a failover event. One membership report is issued immediately after the failover, subsequent packets are sent in each 200ms interval. The valid range is (0 - 255). Defaults to 1. A value of 0 prevents the IGMP membership report from being issued in response to the failover event.
- Specify the number of packets to transmit through a slave before moving to the next one. When set to 0 then a slave is chosen at random.The valid range is (0 - 65535). Defaults to 1. This option has effect only in balance-rr mode.
- Specify the number of peer notifications (gratuitous ARPs and unsolicited IPv6 Neighbor Advertisements) to be issued after a failover event. As soon as the link is up on the new slave a peer notification is sent on the bonding device and each VLAN sub-device. This is repeated at each link monitor interval (ARPIntervalSec or MIIMonitorSec, whichever is active) if the number is greater than 1. The valid range is (0 - 255). Default value is 1. These options affect only the active-backup mode.
- A boolean. Specifies that duplicate frames (received on inactive ports) should be dropped false or delivered true. Normally, bonding will drop duplicate frames (received on inactive ports), which is desirable for most users. But there are some times it is nice to allow duplicate frames to be delivered. The default value is false (drop duplicate frames received on inactive ports).
- Specifies the minimum number of links that must be active before asserting carrier. The default value is 0.
For more detail information see Linux Ethernet Bonding Driver HOWTO
Example 1. /etc/systemd/network/bridge.netdev
[NetDev] Name=bridge0 Kind=bridge
Example 2. /etc/systemd/network/vlan1.netdev
[Match] Virtualization=no [NetDev] Name=vlan1 Kind=vlan [VLAN] Id=1
Example 3. /etc/systemd/network/ipip.netdev
[NetDev] Name=ipip-tun Kind=ipip MTUBytes=1480 [Tunnel] Local=192.168.223.238 Remote=126.96.36.199 TTL=64
Example 4. /etc/systemd/network/tap.netdev
[NetDev] Name=tap-test Kind=tap [Tap] MultiQueue=true PacketInfo=true
Example 5. /etc/systemd/network/sit.netdev
[NetDev] Name=sit-tun Kind=sit MTUBytes=1480 [Tunnel] Local=10.65.223.238 Remote=10.65.223.239
Example 6. /etc/systemd/network/gre.netdev
[NetDev] Name=gre-tun Kind=gre MTUBytes=1480 [Tunnel] Local=10.65.223.238 Remote=10.65.223.239
Example 7. /etc/systemd/network/vti.netdev
[NetDev] Name=vti-tun Kind=vti MTUBytes=1480 [Tunnel] Local=10.65.223.238 Remote=10.65.223.239
Example 8. /etc/systemd/network/veth.netdev
[NetDev] Name=veth-test Kind=veth [Peer] Name=veth-peer
Example 9. /etc/systemd/network/dummy.netdev
[NetDev] Name=dummy-test Kind=dummy MACAddress=12:34:56:78:9a:bc
systemd(1), systemd-networkd(8), systemd.link(5), systemd.network(5)
networkctl(1), systemd.directives(7), systemd.index(7), systemd.link(5), systemd.network(5), systemd-networkd.service(8).
Explore man page connections for systemd.netdev(5).